British Medical Association (BMA) members voted overwhelmingly against the Westminster Government's plans in a poll organised by the trade union, dealing a blow to Prime Minister David Cameron's hopes of an end to the bitter dispute.
It may now ballot for its first industrial action since the 1970s after stating the move would mean GPs working until 68 before they can draw their full pension, huge extra costs in pension contributions for younger doctors and the final salary scheme being replaced by a career earnings-based pension.
Around 46,000 doctors took part in the BMA's survey – a response rate of 36% – with over four in five saying the proposals should be thrown out.
More than a third over the age of 50 said they intend to retire early if the changes go ahead.
The BMA has formally written to the Government rejecting the "final" offer and urging ministers to meet unions to agree fairer changes.
It now aims to work up detailed plans on taking industrial action, adding that all attempts will be made to ensure any action would minimise any risk of harm to patients.
An emergency meeting will now be held on February 25 to decide on the options for balloting on industrial action, unless there is a "significant" change in the Government's position.
Dr Hamish Meldrum, chairman of the BMA Council, said: "The strength and scale of feeling among doctors is abundantly clear – they feel let down and betrayed.
"Doctors are at the forefront of attempts to save the NHS £20 billion, while trying to protect patient care, are in the midst of huge system reform in England, which is causing chaos in many areas, and are about to enter a fourth successive year of a pay freeze."
GPs earn an average of £105,700 with a contract which came into force in 2004 raising salaries by a third in the majority of cases.
The pension reforms broadly mirror those for other public sector workers, except that GPs will be asked to pay higher contributions for longer.
GPs currently paying 8.5% into their pension pot will be asked to contribute 14.5% by 2014, with the retirement age rising to 68, in line with the forthcoming state pension age, for new recruits.
The BMA said along with the loss of the final salary scheme, "the retirement age would increase, with many having to work to 68 before being able to draw a full pension. The amount doctors have to pay into their pension would rise significantly, with those at the start of their careers facing the prospect of paying over £200,000 in additional lifetime contributions."
A UK Department of Health spokesman said GPs can choose to stay on the old pension scheme, where the retirement age remains 65 under the reforms.